Starting up; early stages - Introduction to Environmental Impact Assessment - page 113

Many impact identification methods were developed in response to the NEPA and have
since been expanded and refined. The simplest involve the use of lists of impacts to
ensure that none has been forgotten. The most complex include the use of interactive
computer programmes, networks showing energy flows and schemes to allocate
significance weightings to various impacts. Many of the more complex methods were
developed for (usually US) government agencies that deal with large numbers of fairly
similar project types (e.g. the US Forest Service).
In the UK, the use of impact identification techniques is less well developed. Simple
checklists or, at best, simple matrices are used to identify and summarize impacts. This
may be attributable to the high degree of flexibility and discretion in the UK's
implementation of the EIA Directive, to a general unwillingness in the UK to make the
EIA process over-complex or to disillusionment with the more complex approaches that
are available.
The aim of this section is to present a range of these methods, from the simplest
checklists needed for compliance with regulations to complex approaches that
developers, consultants and academics who aim to further “best practice” may wish to
investigate further. The methods are divided into the following categories:
• checklists
• matrices
• quantitative methods
• networks
• overlay maps.
The discussion of the methods here relates primarily to impact identification, but most of
the approaches are also of considerable (and sometimes more) use in other stages of the
EIA process—in impact prediction, evaluation, communication, mitigation, presentation,
monitoring and auditing. As such, there is considerable interaction between Chapters 4, 5,
6 and 7, paralleling the interaction in practice between these various stages.
For further information on the range of methods available we refer the reader to
Rodriguez with Glasson (2003), Morris & Therivel (2001), Bregman & Mackenthun
(1992), Wathern (1984), Sorensen & Moss (1973), Munn (1979), and Rau & Wooten
(1980).
Checklists
Most checklists are based on a list of special biophysical, social and economic factors
that may be affected by a development. The simple checklist can help only to identify
impacts and ensure that impacts are not overlooked. Checklists do not usually include
direct cause-effect links to project activities. Nevertheless, they have the advantage of
being easy to use. Table 3.5 (ODPM 2003a) is an example of a simple checklist.
Questionnaire checklists are based on a set of questions to be answered. Some of the
questions may concern indirect impacts and possible mitigation measures. They may also
provide a scale for classifying estimated impacts, from highly adverse to highly
beneficial. Figure 4.7 shows part of the EC's (2001b) questionnaire checklist.
Threshold-of-Concern checklists consist of a list of environmental components and,
for each component, a threshold at which those assessing a proposal should become
concerned with an impact. The implications of alternative proposals can be seen by